tests: Adjust test for size overflow
tests: Adjust test for size overflow

This SVG used to result in the error message "Could not get dimensions",
but the actual issue with that SVG is that rendering would overflow the
image surface limits of cairo, which is better described by the error
message that rsvg-convert yields now.

GNOME/librsvg,GNOME/librsvg,GNOME/librsvg,GNOME/librsvg